The present invention relates to a needle guide for a medical imaging instrument. More particularly, the invention is directed to an apparatus and method for guiding needles into selected locations of a patient relative to a medical instrument imaging sensor. The needle guide facilitates entry of a needle through the skin of a patient at an initially obtuse angle to the skin, and then allows the needle to be directed into the patient at a more acute angle after the skin has been pierced.
Imaging instruments, such as ultrasound probes, computed tomography scanners (CT Scanners), and magnetic resonance imagers (MRI) have revolutionized the manner in which many important medical procedures are performed. Each of these medical instruments utilizes substantially non-invasive imaging techniques to explore and assess the condition of sub-dermal tissue. As a result of these non-invasive imaging techniques, diagnostic and therapeutic protocol""s have been developed that allow for the provision of many highly successful and safe procedures that can be performed with a minimum of disturbance to patients.
Ultrasound, for example, has received widespread acceptance as a useful diagnostic tool. Ultrasound is particularly well suited for obstetrics, where real-time scanners create a continuous image of a moving fetus that can be displayed on a monitoring screen. The image is created by emission of very high frequency sound waves from a transducer placed in contact with the mother""s skin. Repeated arrays of ultrasonic beams scan the fetus and are reflected back to the transducer, where the beams are received and the data transmitted to a processing device. The processing device analyzes the information and composes a picture for display on the monitoring screen. Relative measurements may be made, and the gestational age, size and growth of the fetus can be determined. In some circumstances, a needle is guided into amniotic fluid in order to retrieve a fluid sample for analysis. These samples can be useful for diagnosing irregular conditions and can indicate that prenatal care is necessary for the fetus.
Ultrasound probes, and other imaging instruments, are also used for a variety of other purposes, such as identifying the existence, location, and size of tumors, as well as the existence of other medical conditions, including the atrophy or hypertrophy of bodily organs. Ultrasound probes are also useful for inserting catheters into blood vessels and bodily organs. While many imaging techniques are primarily performed on humans, similar techniques are often used by veterinarians to diagnose and treat animals, such as sheep, cows, horses, and pigs.
For many imaging applications, it is desirable that a needle, biopsy instrument, catheter, or other thin instrument (hereafter generalized as xe2x80x9cneedlexe2x80x9d or xe2x80x9cneedlesxe2x80x9d) be inserted into the body of a patient in order to remove a biopsy sample or to perform other medical procedures. It is normally desirable that the needle be guided to a specific position within the body of the patient. Various guide devices have been designed for assisting in directing the needle. Many of these guides are fixed-angle devices with limited functionality because they have limited control over needle placement compared to a guide that would allow selection of multiple angles. In addition, many of these devices do not permit the placement of more than one needle into a patient or they do not make such multiple placements easy.
One particular problem with many needle guide devices is that they do not permit the needle to readily change angular direction during insertion into the skin or after insertion through the skin of a patient. Thus, such prior art devices allow each needle to assume only one angle with respect to the skin. This single angle can be problematic when the needle is desirably inserted at one angle but is then preferably advanced deeper into a patient at a different angle after the skin has been pierced. Although some prior art systems allow the needle to be removed from the needle guide during adjustment of the angle, this can be a clumsy and uncomfortable undertaking.
The problem of changing the needle angle is particularly pronounced in circumstances when it is desired to direct the needle into a shallow target just below the surface of the skin. Such placement is problematic because the needle must be fixed at a relatively acute angle to the skin and this acute angle means that the needle must pass through a greater distance of skin than would be passed through if the angle were more obtuse. Thus, it would be advantageous to be able to direct the needle into the skin at a first angle that is relatively obtuse to the skin surface and then change the angle to be relatively acute in order to penetrate to the shallow target. Unfortunately, most existing needle guides do not allow the angle to easily change during a medical procedure.
Another specific problem with many current needle guide systems is that they are not well suited to be used with a sterile cover, such as a latex film, placed over the imaging instrument. Such covers are increasingly desirable in order to maintain the ultrasound sensor in a sterile environment. The covers reduce the likelihood of contamination between patients and reduce the cost of medical procedures by minimizing sterilization costs. One challenge of working with latex and similar polymer based covers is that they have a high coefficient of friction and are subject to binding when in contact with moving pieces of an imaging sensor or needle guide. Such binding can lead to tears or punctures of the cover. For example, some prior art imaging sensors have removable pieces that are frictionally fit over a latex cover. Such designs are problematic because they can be difficult to fit and remove, as well as cause problems with binding and an ensuing risk of tearing.
Consequently, a need exists for an improved needle guide system. Such improved needle guide system should permit a needle to be directed into a patient at a variety of angles and allow for the easy removal of the needle from the system without damage to a protective cover.
The present invention is directed to a needle guide system for use in guiding a needle into a patient who is undergoing imaging analysis. The needle guide includes a body having a slot into which is placed a needle shaft. The slot has two interior surfaces that are positioned opposite one another and combine to define a plane of movement in which the needle can pivot. The needle stays within this plane while being inserted into the patient, but can be freely tilted within the plane, and thus can take numerous angles relative to the surface of the skin. With the present invention, the angle of the needle can change, yet the point at which the needle contacts the skin of a patient can remain the same. Thus, the needle can rotate along a pivot point at the spot where the needle comes in contact with the skin.
In certain implementations, the plane of movement is substantially perpendicular to the surface of the skin of the patient. In addition, in particular embodiments, the depth of the slot in the needle guide is non-uniform over the length of the slot. The non-uniform depth allows a plane to be formed in which the needle may be tilted and aligned, but also allows more of the needle to be exposed in order to facilitate handling by a medical professional conducting the imaging analysis. In some implementations the depth of the slot is greatest at the portion of the slot proximate the patient, while in other implementations the depth of the slot is greatest at the portion of the slot substantially intermediate the ends of the slot, while in still other implementations the depth of the slot is greatest at the portion of the slot distal from the patient.
The distance between the interior surfaces of the slot can be varied in order to allow the slot to accommodate a variety of widths of needle. The slot can be narrow to accommodate a narrow needle, or wide to accommodate a wide needle. The variation of slot width can be accomplished by, for example, insertion of a separate piece into the slot to narrow it, or by having the width of the slot mechanically varied by being screwed or clamped to determine different slot dimensions.
In specific implementations, the needle guide system includes a bracket and a mounting base in addition to the actual needle guide. The mounting base secures the needle guide to the bracket, and the bracket secures the mounting base to an imaging instrument, such as an ultrasonic probe. While the bracket may be separable from the probe, it may also be integrally formed thereto and in essence be one piece with the probe.
The needle guide system of the present invention is designed such that it may be used with a protective cover placed over the bracket and mounting base. The needle guide is configured to be removably secured to the mounting base over the protective cover, without the development of significant kinetic friction between the protective cover and the needle guide during mounting and removal of the needle guide. As such, the disposable needle guide may be placed on the mounting base, and removed therefrom, with minimal mechanical stress to the protective cover, thereby preventing holes in the protective cover from developing and maintaining a sterile environment around the imaging instrument.
In specific implementations of the present invention, the needle guide further includes a movable locking member having an unlocked configuration in which the locking member does not apply pressure to the mounting base, while also having a locked configuration in which the locking member does apply pressure to the mounting base. The locking member may be alternated between a locked and an unlocked configuration without applying significant kinetic friction to the protective cover.
In certain implementations, the bracket of the present invention includes two paired arms for securing the needle guide system to an imaging instrument in specific implementations. As noted above, the bracket may be integrally formed with the imaging instrument to be one piece. The paired arms are configured to apply a compressive force to the imaging instrument, and the imaging instrument is an ultrasonic probe in specific implementations.
The above summary of the present invention is not intended to describe each discussed embodiment of the present invention. This is the purpose of the figures and the detailed description which follow.